For many, this is a time to be spent with loved ones. Others have no such luck. Year after year, surveys indicate that half a million pensioners spend Christmas Day alone. Isolation is not only an affliction for the elderly; last year, ChildLine dealt with 8,800 requests for counselling over the 12 days of Christmas – up 26% over 2010. The top two problems were "family relationships" and "depression".

Loneliness is not just for Christmas and it is certainly more than an emotional problem. Researchers have shown that day-in, day-out, chronic isolation does real, physical damage, leading to higher blood pressure, increased stress and less and lower-quality sleep. Indeed, those who perceive themselves to have few meaningful social connections are more likely to die earlier. A recent international study led by the American psychologist Julianne Holt-Lunstad found that involuntary loneliness carries a higher mortality risk than air pollution or obesity.

In some respects, the scientists are merely affirming what the poets have always known. At the age of 12, Alexander Pope wrote an ode pointing out how unchosen solitude is the most lethal kind: "Thus let me live, unseen, unknown; / Thus unlamented let me die." But while research is still relatively recent, academics are also adding to our knowledge of this area. One of the subject's foremost researchers, neuroscientist John Cacioppo, has shown that loneliness is actually contagious. In a study of almost 5,000 Massachusetts residents he carried out over 10 years, Mr Cacioppo found that a friend of a lonely person was 52% more likely to develop feelings of social rejection – and in turn one of their friends was 25% more likely to feel lonely. And the chain went on: a friend of a friend of a friend of a lonely person was also at heightened risk of loneliness. View loneliness as a social disease, rather than an individual affliction, and you see the limits of our current approach to the problem.

While charities such as the WRVS and Esther Rantzen's new Silver Line offer undoubtedly valuable help for older people, this is not just a problem for one demographic – even if, typically, poorer health makes social isolation of the elderly particularly difficult and dangerous. But the isolation of individuals is the inevitable result of a society that has less time for the people living in it. Researchers in China report that its 30-year boom has gone hand-in-hand with a weakening of the old Confucian social ties and rising alienation. This is the flipside of that other new science, of happiness, and both point to a fundamental flaw in societies that pay excess attention to economic growth above bonds of community.